It has become commonplace today in the consumer and residential sector to use fabric softening compositions comprising major amounts of water, lesser amounts of fabric softening agents, and minor amounts of optional ingredients such as perfumes, colorants, preservatives and stabilizers. Such compositions are aqueous suspensions or emulsions that are conveniently added to the rinsing bath of residential washing machines to improve the softness of the laundered fabrics.
It is an entirely different situation, however, to find similarly acting liquid fabric softening compositions that are effective in the harsher conditions found in industrial and institutional settings without imparting negative effects on the fabric. That is, in the industrial sector fabric softening agents generally cause undue premature yellowing of the fabrics. By the term, “industrial and institutional” it is meant that the operations are located in the service industry including but not limited to hotels, motels, hospitals, nursing homes, restaurants, health clubs, and the like. Due to a number of factors, fabric is exposed to considerably harsher conditions in the industrial and institutional setting as compared to the consumer or residential sector. In the industrial and institutional sector, soil levels found in the linens are much higher than in the residential or consumer sector that are less alkaline. Wash cycles in the residential sector have a near neutral pH whereas the wash cycles in the industrial and institutional sector have a pH of greater than about 9.
Another factor that contributes to the overall differences in operating conditions between consumer laundry and that in the industrial and institutional setting is the high volume of laundry that must be processed in shorter times in the industrial and institutional sector than allowed in the consumer market. Dryers in such operations operate at substantially higher temperatures than those found in the consumer or residential market. It is expected that industrial or commercial dryers operate at levels to provide fabric temperatures that are typically provided in the range of between about 180 degrees Fahrenheit and about 270 degrees F., whereas consumer or residential dryers often operate at maximum fabric temperatures of between about 120 degrees F. and about 160 degrees F. It should be understood that the temperature of the consumer or residential dryer is often changed depending upon the item being dried. Even so, residential dryers do not have the capacity to operate at the elevated temperatures found in the industrial and institutional sector. Industrial and institutional dryers operate in the range of about 180 degrees up to about 270 degrees Fahrenheit, more preferably, about 220 degrees up to about 260 degrees F., and most preferably about 240 degrees up to about 260 degree Fahrenheit maximum fabric temperature.
Many different types of fabric softening agents are used in commercially available fabric softeners intended for the residential or consumer market, for example quaternary ammonium compounds. Fabric softeners containing quaternary ammoniums operate quite well in the near neutral pH wash and lower dryer temperature conditions of the residential market. Softeners containing quaternary ammonium compounds impart softness to the laundry and are non-yellowing in the residential and consumer sector. These traits are a highly desired combination of properties for textiles such as fibers and fabrics, both woven and non-woven. By the term “softness” it is meant the quality perceived by users through their tactile sense to be soft. Such tactile perceivable softness may be characterized by, but not limited to resilience, flexibility, fluffiness, slipperiness, and smoothness and subjective descriptions such as “feeling like silk or flannel.”
In contrast, Applicants discovered that the quaternary ammonium compounds, when used in the harsher conditions found in the industrial and institutional sector, caused unacceptable yellowing of the fabric. The majority of the linens in the institutional and industrial sector are white. As can be expected, such yellowing is much more apparent with white linens. The yellowing gives the linens an unclean or unsavory appearance at best. As such, the use of quaternary ammonium fabric conditioners which cause yellowing may provide a nice feel, but shorten the overall life of a linen because the linen must be discarded before its otherwise useful life is exhausted. In the case of colored linens, yellowing is less obvious but the quaternary ammonium compounds cause a dulling of the colors over time. It is easily appreciated that it is desirable to provide a fabric conditioning agent that does not cause significant yellowing or dulling of fabrics that are repeatedly washed and dried. Moreover, it is generally desirable for white laundry that is dried to remain white even after multiple drying cycles. That is, it is desirable that the fabric not yellow or dull after repeated cycles of drying in the presence of the fabric conditioning composition.
Applicants found that in the higher alkalinity and higher temperature conditions of the industrial and institutional sector the addition of amino silicone or amino-functional silicone to fabric conditioning compositions containing quaternary ammonium compounds did not alter certain fabric conditioning properties. Surprisingly, Applicants found that the combination of amino-functional silicone and quaternary ammonium compounds in the fabric conditioning composition exhibited reduced yellowing or dulling of the laundry in industrial and institutional conditions without adversely affecting the softening properties.
It is known in the art to include anti-wrinkling agents to provide anti-wrinkling properties. Exemplary anti-wrinkling agents can include siloxane or silicone containing compounds. While it is known in the art to include silicones in fabric conditioning compositions to aid in anti-wrinkling, it has not previously been known to add silicones having amino functional groups for use in high temperature dryers such as found in industrial and institutional settings. Moreover, it has not been known to add amino functional silicones to fabric conditioning compositions in order to reduce the yellowing of fabrics often experienced in the industrial and institutional sector due to the extreme conditions. It has also not been known to include silicones in fabric conditioning compositions in order to reduce yellowing of fabrics when using high alkaline detergents.
Fabric conditioning or fabric softening compositions are delivered via various methods. Liquid softeners are common in the residential market as are dryer sheets. Yet another method of delivery is via a solid block. An advantage of a solid block is that it is more sustainable due to the reduction in packaging and reduces shipping costs. Further advantages are that the solid compositions of the present invention have an attractive appearance both as a solid and when dispersed as a liquid.
The present invention provides a solid block fabric softening composition by combining quaternary ammonium salts with a silicone emulsion and further incorporates surfactants in a water soluble carrier such as urea.